Utilization of red mud for the preparation of lightweight aggregates
The few reuse and large stockpile of red mud led to a series of social and environmental problems. Preparation of lightweight aggregates (LWA), using red mud as main raw material, and waste glass and bentonite as additives, was investigated in this study, and the crystalline phases and internal structure of the obtained LWA were characterized. The optimum preparation conditions of LWA were as following: the weight ratio of red mud/ waste glass/ bentonite at 70:15:15, heating at 550°C for 15min, sintering at 1120°C for 40min, under which the LWA with the bulk density of 1.08 g·cm-3, water absorption rate (WAR) of 10.45 % and cylinder compressive strength (CCS) of 8.22 MPa was obtained, and met the requirements of GB/T 17431.1-1998 for LWA. The crystalline phases present in the LWA mainly was gehlenite, andradite and schorlonite, different from calcite, hematite and calcium titan ate in red mud based on XRD, which were observed with the abundant pores in the internal structure of the LWA based on the digital photo.